1. Field of the Invention
This invention relates to a method of forming a patterned transparent electro-conductive film on a substrate. More particularly, it relates to a method of forming a transparent electro-conductive film possessing stable, low electrical resistivity in precise patterns on a substrate. The substrate coated with the film can be effectively used in liquid crystal displays.
2. Description of the Prior Art
Transparent electrode plates prepared by depositing transparent electro-conductive films in desired patterns on substrates such as glass plates have been used for liquid crystal displays. It has been required of the patterned electro-conductive films that they be chemically inert, mechanically firm, have low electrical resistivity, have high transmittance and the ability to form precise patterns. Heretofore, transparent electrode plates have been prepared by forming a predetermined pattern on a substrate by photo-etching after depositing a transparent electro-conductive film on the substrate. The conventional methods of forming the electrode plates have been complicated because of the sophisticated apparatus required and the labor involved, both of which limit the productivity of the electrode plates. Thus, the production efficiency has been low, because of the many steps involved and the expense of the process. Accordingly, the advantages of the conventional process have been limited from the industrial point of view.
Another conventional method of forming a patterned electro-conductive film on a substrate has been to deposit the film on a substrate by using a metal mask under vacuum deposition conditions. However, when a patterned electro-conductive film is formed on a substrate using the metal mask method, it has been difficult to form precise patterns on the substrates since close contact between the metal mask and the substrate is difficult to achieve. This is especially difficult under high vacuum conditions. A need therefore, exists for a method for forming patterned electro-conductive films on substrates which is accomplished in a few steps in high productivity and with high production efficiency.